The present invention relates, in general, to tissue dissection and retraction and, in particular, to a new and useful endoscopic method for performing optical tissue dissection and retraction with a novel device that is utilized in carrying out the method in support of a surgical procedure such as a coronary bypass procedure or other type of vessel harvest procedure.
It is a common practice in the surgical field to dissect tissue in order to accommodate various surgical procedures. One type of useful tissue dissector is a balloon dissector such as the device embodied in U.S. Pat. No. 5,607,441. This device is particularly useful for dissecting between tissue layers in order to create space between the dissected layers. Accordingly, it is common to use the balloon dissector in endoscopic surgical procedures such as a laparoscopic hernia repair, laparoscopic bladder neck suspension or lymph node dissection.
Additionally, it has also become common practice to conduct minimally invasive or endoscopic tissue dissection and vessel harvest in a patient in order to facilitate a coronary artery bypass grafting procedure ("CABG"). For instance, vessels such as the saphenous vein are harvested using a minimally invasive tissue dissection method for use in a CABG.
SU 1371689 teaches a vessel removal procedure which utilizes an endoscope having a lumen therethrough. In this procedure, the small saphenous vein is grasped and held with a grasper which is introduced through the lumen of the endoscope. After connective tissue has been dissected from around the vein, the vein is then ligated and transected and removed from the lower limb of the patient through the lumen of the endoscope.
Essentially, the same technique for removal of a vessel is disclosed in U.S. Pat. No. 5,373,840 which pertains to a method for harvesting a vessel such as the saphenous vein. This procedure also utilizes an endoscope having a lumen therethrough which permits the saphenous vein to be grasped by a grasping instrument and dissected. As the vein is withdrawn into the lumen of the endoscope, the endoscope is maneuvered along the length of the vein while side branches of the vein are ligated and transected whenever encountered.
Although this method provides for a minimally invasive technique, there are several drawbacks associated with this procedure. First, in practicing this method, there is limited visibility of the saphenous vein and its side branches because viewing is limited to the immediate area directly in front of the endoscope. Secondly, the illumination within the subcutaneous space created by this type of endoscope is also limited to the light emitted directly at the distal portion of the endoscope. Another drawback to this type of procedure is that the side branches of the saphenous vein limit the maneuverability of the endoscope since the outer edge of the endoscope body is prevented from advancing along the trunk of the saphenous vein until the encountered side branches are ligated and transected thereby. Once freed, the endoscope is then maneuvered until the next side branch is encountered. Moreover, it has been found that methods which utilize this type of endoscope, i.e. an endoscope having a lumen, provide a working space which is very restricted because the side walls of the scope body confine the working instrumentation to a limited area.
Furthermore, the vessel harvesting method described above is typically a three-handed approach which actually requires more than one individual. In this method, one hand is required to hold and maintain the endoscope in position, while a second hand is required to hold the free end of the transected vessel with a grasper and a third hand is required to dissect connective tissue away from the vessel.
Another method for harvesting the saphenous vein is disclosed in "Vein Harvest", Alan B. Lumsden and Felmont F. Eaves, III, in Endoscopic Plastic Surgery (Quality Medical Publishing, Inc., 1995), pp. 535-543. This method provides for performing a preliminary dissection of the saphenous vein while using an open technique prior to inserting an endoscopic retractor such as those commonly used in plastic surgery. A typical endoscopic retractor is the Emory Endoplastic Retractor sold by Snowden-Pencer. In this procedure, once the subcutaneous tissue is retracted with the endoretractor, a pair of disposable 5 mm Metzenbaum laparoscopic scissors are used to dissect the superior surface of the saphenous vein in order to expose the vein. The speed of the dissection of the saphenous vein in this procedure is limited by the spreading motion of the scissor blades as well as the care which must be exercised by the surgeon when dissecting the vein in this manner.
Additionally, it is known to use another type of balloon dissector such as the devices shown in U.S. Pat. Nos. 5,591,183 and 5,601,581 in order to conduct tissue dissection in a patient's leg for harvesting the saphenous vein. These devices and the method for using the devices require placing a cannula into the patient's leg near the saphenous vein and inflating a balloon or plurality of balloons in order to dissect tissue away from the vein for providing space near the vein to facilitate the harvest procedure.
One very successful vessel harvest method is the method developed and promoted by Ethicon Endo-Surgery, Inc., Cincinnati, Ohio. This method utilizes an optical tissue dissector known as the ENDOPATH SUBCU-DISSECTOR.TM. which is used to separate subcutaneous tissue away from the saphenous vein. There is also an optical tissue retractor known as the ENDOPATH SUBCU-RETRACTOR.TM. which is used to retract the dissected tissue away from the saphenous vein. Both of these devices utilize a transparent concave working head having a spoon-shape. The concave working head defines a working space that permits instrumentation to be inserted therein in order to facilitate the vessel harvest procedure. Moreover, both of these devices allow an endoscope to be insertably positioned and held at the working head in order to perform tissue dissection and retraction under direct visualization.
Since the transparent working head is used in the warm tissue of patient's leg, there is a tendency for the endoscope lens and the transparent working head to experience condensation or fogging. This is primarily caused by the difference in temperature between the warm moist environment of the patient's leg and the colder, sterile environment of the operating room which tends to be maintained at 60.degree. to 68.degree. F.
The fogging of the working head and the endoscope lens decreases visualization through the endoscope and results in a blurry image of the operating environment within the working space exhibited on the operating room monitor. Thus, it is common for the surgeon or physician assistant to remove the device from the patient's leg in order to clean the endoscope lens or continue with the procedure by introducing a suction device into the working space for clearing the fogging. In either situation, the length of time required to complete the procedure is increased.
Another situation that is sometimes encountered when using the transparent working head, is that it is common to use an energy-based device such as RF electrosurgical scissors or an ultrasonic surgical device such as the ULTRACISION.TM. LCS Laparoscopic Coagulating Shears manufactured and sold by Ethicon Endo-Surgery, Inc. in order to ligate and transect the side branches of the saphenous vein. Both of these devices are used in the working space defined by the transparent working head.
In cases where an RF electrosurgical device is used, the RF cutting and coagulation of tissue will result in a discharge of smoke that is trapped within the transparent working head resulting in a significant decrease in visibility through the endoscope for the surgeon.
Additionally, for those cases where the ULTRACISION.TM. device is used, there is a fine mist which is produced and becomes trapped within the transparent working head. This mist has an effect on the surgeon's viewing ability by obscuring visibility within the transparent working head.
Presently, there is no known optical dissection and retraction device that eliminates the problems and inconveniences outlined above.